Lark Voorhies

It's been more than two decades since fans bid farewell to Saved by the Bell and TV's beloved gang of teenagers, but before Jimmy Fallon brought together some of the cast for a skit on The Tonight Show on Wednesday, PEOPLE had a Bayside reunion of our own.

The wait is almost over for Saved by the Bell fans. The hotly anticipated The Unauthorized Saved by the Bell Story is less than a month away and Lifetime has released its official poster exclusively to PEOPLE.

The clip shows the Elizabeth Berkley character (who played Jessie Spano) trying to de-escalate the competition between Lark Voorhies (Lisa Turtle) and Tiffani Thiessen (Kelly Kapowski) for the attention of Mark-Paul Gosselaar (Zack Morris), while Dustin Diamond (Screech Powers) tries to keep up with the physical prowess of Mario Lopez (A.C. Slater). And all the while, the six teens ignore adult direction – pretty much your average high school dynamic.

Diamond's 2009 book, Behind the Bell told of less-PG activities, like drug use and sex, but Lifetime claims their story is unrelated to the tell-all, and is instead based on new interviews with those associated with the show.

Hey, hey, hey, hey – what is going on here? This year marks Saved by the Bell's 25th anniversary: The show, which premiered in August 1989, has spent nearly a quarter century in the pop culture matrix.

As Zack Attack sang on Saved by the Bell, Elizabeth Berkley and her former costars are indeed "friends forever."

"It's amazing," Berkley, 41, told PEOPLE backstage Monday at Dancing with the Stars. "I don't know if you have people from high school who you're still close with, [but] even if we don't see each other for a long time, it's a connection that we'll have forever."

"Luckily we do check in, and we always have each other's backs," she adds. "It's a really special thing."

In 2003, Lark Voorhies and Dustin Diamond reunited after many years to record commentary for a Saved by the Bell box set. But it wasn't the Screech-and-Lisa reunion he expected.

"I was always used to playing off of her and looking into her eyes," Diamond says of his former costar. "When I saw her at the commentary, it wasn't the Lark I knew."

Voorhies stared into space, Diamond says, much like she did during a series of interviews with PEOPLE. Voorhies says she is spiritual, but her mother Tricia revealed her daughter was diagnosed with bipolar disorder.

She wasn't always like this. Voorhies, who famously played the bubbly Lisa Turtle on the '90s Saturday morning sitcom, was just as engaging offscreen, recalls Mario Lopez.

The former teen star, known to a generation of fans as the fashionable Lisa Turtle, denies anything is wrong, but after a bizarre Yahoo! video went viral earlier this year, some questioned whether drugs played a role. Voorhies adamantly denied it. Instead, her mother says, she has been diagnosed with bipolar disorder.

In a series of interviews with PEOPLE, it was clear something wasn't right. Voorhies, 38, would frequently stop mid-sentence and stare off, often mumbling to herself or to others who weren't there.

"There are things that have traumatized her," says Tricia, 64, who shares a home with her daughter in Pasadena, Calif. "I care deeply about my daughter and I want her to resume her life."